Groups

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                            GROUP

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Groups are basically windows inside windows. They allow to subdivide space in a window to layout widgets as a group. Almost all more complex widget layouting requirements can be solved using groups and basic layouting fuctionality. Groups just like windows are identified by an unique name and internally keep track of scrollbar offsets by default. However additional versions are provided to directly manage the scrollbar.

Usage

To create a group you have to call one of the three nk_group_begin_xxx functions to start group declarations and nk_group_end at the end. Furthermore it is required to check the return value of nk_group_begin_xxx and only process widgets inside the window if the value is not 0. Nesting groups is possible and even encouraged since many layouting schemes can only be achieved by nesting. Groups, unlike windows, need nk_group_end to be only called if the corresponding nk_group_begin_xxx call does not return 0:

if (nk_group_begin_xxx(ctx, ...) {
    // [... widgets ...]
    nk_group_end(ctx);
}

In the grand concept groups can be called after starting a window with nk_begin_xxx and before calling nk_end:

struct nk_context ctx;
nk_init_xxx(&ctx, ...);
while (1) {
    // Input
    Event evt;
    nk_input_begin(&ctx);
    while (GetEvent(&evt)) {
        if (evt.type == MOUSE_MOVE)
            nk_input_motion(&ctx, evt.motion.x, evt.motion.y);
        else if (evt.type == [...]) {
            nk_input_xxx(...);
        }
    }
    nk_input_end(&ctx);
    //
    // Window
    if (nk_begin_xxx(...) {
        // [...widgets...]
        nk_layout_row_dynamic(...);
        if (nk_group_begin_xxx(ctx, ...) {
            //[... widgets ...]
            nk_group_end(ctx);
        }
    }
    nk_end(ctx);
    //
    // Draw
    const struct nk_command *cmd = 0;
    nk_foreach(cmd, &ctx) {
    switch (cmd->type) {
    case NK_COMMAND_LINE:
        your_draw_line_function(...)
        break;
    case NK_COMMAND_RECT
        your_draw_rect_function(...)
        break;
    case ...:
        // [...]
    }
    nk_clear(&ctx);
}
nk_free(&ctx);

Reference

Function	Description
nk_group_begin	Start a new group with internal scrollbar handling
nk_group_begin_titled	Start a new group with separated name and title and internal scrollbar handling
nk_group_end	Ends a group. Should only be called if nk_group_begin returned non-zero
nk_group_scrolled_offset_begin	Start a new group with manual separated handling of scrollbar x- and y-offset
nk_group_scrolled_begin	Start a new group with manual scrollbar handling
nk_group_scrolled_end	Ends a group with manual scrollbar handling. Should only be called if nk_group_begin returned non-zero
nk_group_get_scroll	Gets the scroll offset for the given group
nk_group_set_scroll	Sets the scroll offset for the given group